The power transmission chain for use in the continuously variable transmission (CVT) for automotive vehicles includes, for example, an endless type which is entrained between a drive pulley on an engine side and a driven pulley on drive wheel side. The continuously variable transmission transmits a great power by way of contact between sheave surfaces of the respective pulleys and end faces of pins of the power transmission chain under boundary lubrication. Furthermore, the continuously variable transmission is adapted to accomplish continuous gear shifting by continuously varying a respective groove width of the pulleys.
The above power transmission chain includes one which is manufactured by a method wherein a plurality of link plates formed with through-holes are stacked in layers and the pins are inserted through the through-holes placed in intercommunicating relation for interconnecting the link plates by way of fit-engagement between the pins and the link plates. In this case, the manufacture of the power transmission chain requires quite a labor-intensive operation because the chain must be fabricated as ensuring the fit-engagement between the link plates and the pins.
In this connection, a method facilitating the assembly of the power transmission chain is disclosed in Patent Gazette No. 2851063. According to this method, a large number of link plates are arranged in overlapping relation. Subsequently, one set of overlapped link plates are clamped between two extrusion pins each formed with projection(s) and depression(s) at a distal end thereof and the link plates are mutually shifted to conform to the projection(s) and depression(s). The pins are inserted through the link plates in this state. This procedure is repeated to interconnect the link plates into a straight chain. Finally, opposite ends of the link plate chain are combined with each other.
However, the above assembly method of power transmission chain requires the step of combining the opposite ends of the link plate chain. In the case of a power transmission chain having a specific pin configuration or a specific configuration of the through-hole of the link plate, the assembly method requires a special component for the combining portion or requires complicated operations such as to align the through-holes of the link plates with the corresponding pins. This takes quite a large quantity of time and labor.
In view of the foregoing, it is an object of the invention to provide a manufacture method of power transmission chain which includes a decreased number of steps and provides an easy assembly of the chain.